Epitopes capable of generating neutralizing antibodies against poliovirus have never been developed using sub-viron particles. The three or four epitopes on each of the three types of intact virion that generate neutralizing antibodies are all conformational epitopes. The fundamental goal of this work is to find peptide sequences that exist outside the intact virion, that can generate neutralizing antibodies against poliovirus. If peptides are found using one of the combinatorial systems, the amino acid sequences are likely to form "mimeotopes" of the native epitopes (i.e., peptide sequences that conformationally mimic native epitopes rather than show sequence identity with native epitopes). Demonstration of the existence of such non-native, peptide epitopes would have significant impact on the development of assays for vaccine potency and enhance our understanding of immunogenicity of the vaccine. Moreover, the discovery of peptide mimeotopes of neutralizing poliovirus epitopes would allow the development of a nonviral based vaccine, with significant financial savings as compared to inactivated vaccine derived from live poliovirus grown in a monkey kidney cell line. This laboratory has a series of neutralizing monoclonal antibodies (Mabs) specific for the three types of poliovirus. These Mabs form the basis of the monoclonal ELISA for potency of inactivated poliovirus vaccine (IPV) that has been developed in this laboratory. We will use these Mabs in an attempt to select, from random peptide combinatorial libraries, sequences capable of binding to the polio specific monoclonals. These sequences can be enriched by repetitive selections. We have developed selection procedures using a random library containing varying epitopes of 8 aa on a phage display backgound and are evaluating the results from selection with one polio virus Type 2 monoclonal. The possible advantages of other display systems will also be evaluated.